1. Field of the Disclosure
The present disclosure relates generally to optical communication networks and, more particularly, to flexible virtual optical network provisioning using distance-adaptive modulation.
2. Description of the Related Art
Telecommunication, cable television and data communication systems use optical networks to rapidly convey large amounts of information between remote points. In an optical network, information is conveyed in the form of optical signals through optical fibers, also referred to as a lightpath.
Software-defined networking (SDN) represents an important step towards network virtualization and/or abstraction and may allow for a logical network entity to be instantiated automatically using software instructions, rather than manually from user input. In this manner, SDN may enable flexible definition of virtual networks. For example, using the OpenFlow communications protocol managed by The Open Network Foundation (ONF), a traffic flow entity may be instantiated using an arbitrary combination of layer identifiers defined in a header space. OpenFlow may use various combinations of traffic identifiers (Internet-protocol (IP) addresses, media access controller (MAC) addresses, port addresses, etc.) at various layers to define a traffic flow. Then, by installing and configuring packet-forwarding rules associated with the flow to physical switches, an OpenFlow controller may ensure that the traffic flow entity instantiates a path that is routed through a network including the physical switches.
OpenFlow's FlowVisor may instantiate a virtual network entity (called a “slice”) by associating multiple traffic flow entities with a given slice, whereby each slice is managed by a separate tenant controller, allowing the tenant to control over a portion of network traffic and a subset of the physical network. In OpenFlow, multiple flowspaces may be defined for each network switch. Each flowspace may be associated with a slice, which in turn is managed by a separate controller. FlowVisor may ensure that actions in one slice do not affect another by intercepting and rewriting OpenFlow messages.
The principles and features of SDN technologies were initially deployed with a focus on internet protocol (IP) and Ethernet networks. However, the concept of SDN may be introduced to optical networks as well. For example, the SDN concept may be applied to agile optical networks built using colorless/directionless/flex-grid reconfigurable optical add-drop multiplexers (ROADMs) and multiple modulation formats programmable transponders. An SDN-enabled optical network may be referred to as a Software-Defined Optical Network (SDON), which may be more open, programmable, and application aware. A feature of SDON is optical network virtualization, which may enable network service providers to provision multiple coexisting and isolated virtual optical networks (VONs) over the same physical infrastructure. For example, in conventional optical networks, network services are provided in terms of lightpaths (i.e., optical network paths between given endpoints). In SDONs, network services may be provided in terms of VONs. When provisioning VONs in response to a request, different mapping patterns for mapping a virtual node to physical topology may be possible.